Activation of alveolar macrophages following infection with the parasitic nematode Nippostrongylus brasiliensis.

Alveolar macrophages (AM) of rats infected with 3000 Nippostrongylus brasiliensis infective larvae for 2, 8 or 32 days (D2, D8 or D32 AM) quantitatively surpassed AM from uninfected rats in one or more of IgG- or C3-dependent phagocytosis indices, beta-D-glucuronidase release, or spontaneous release of thymocyte activating factor (interleukin-1, IL-1) and hepatocyte stimulation factor (HSF). These observations suggest that N. brasiliensis infection results in the activation of AM. We have reported previously that a greater proportion of AM from infected rats expressed C3 receptors and were helminthocidal in vitro in the presence of complement than normal AM which were not helminthocidal. The acquisition of the activated state by AM during infection may play a role in vivo lung resistance against migrating helminth parasites.